The battery has become a primary power source for many portable electronic devices, such as radios, hearing aids, watches, calculators and the like. In order to maintain the overall electronic device as compact as possible, the electronic devices are usually designed with cavities to accommodate miniature batteries as their source of power. The cavities are usually made so that a battery can be snugly positioned therein, thus making electronic contact with appropriate terminals within the device. A major potential problem in the use of battery powered devices of this nature is that if the battery bulges, it usually becomes wedged within the cavity of the device which sometimes can result in damage to the device. Another problem with the manufacture of miniature electronic devices is that it is not always possible to provide adequate spacing or cavities to accommodate standard-type miniature cells, such as button cells. A specific example of this is in the digital readout watches and the wafer-thin calculators. Thus in order to provide a sufficient power source for these devices, the battery industry has resorted to not only miniaturization of the battery but to also exploring different types of active battery components which will provide long service. For example, recently developed electrochemical cell systems that will provide a long service life utilize highly reactive anode materials, such as lithium, sodium and the like in conjunction with high energy density liquid cathode materials and nonaqueous electrolytes. However, in the employment of these types of cell components, the conventional cylindrical cell or button cell type construction has been resorted to.
The battery industry has also resorted to flat-type cell constructions for use in portable electronic devices having cavities to accommodate the flat cell construction. However, the flat-type battery constructions usually employ cathode and anode components that are relatively rigid in nature and thus cannot be bent to any appreciable degree without affecting the electrochemical reactions of the cell. Thus the portable electronic device industry has been required to provide definitive size cavities within the device to accommodate relatively rigid cylindrical or flat-type constructed batteries.
It is, therefore, a primary object of this invention to provide a thin, flexible electrode strip which can be employed to produce a flexible battery which can be bent to accommodate a curvilinear cavity within the device so as to give the electronic device industry greater flexibility in the design of electronic devices.
Another object of the present invention is to provide a thin, flexible electrode strip that can be bent 180.degree. around a radius of 1.25 inches (3.175 cm) or less without cracking or chipping at room temperature (i.e., about 20.degree. C.).
Another object of the present invention is to provide a thin, flexible battery that can be bent into a curvilinear configuration without affecting its electrochemical performance.
Another object of the present invention is to provide a thin, flexible cathode strip comprising an active cathode material and a minor amount of an ethylene acrylic acid polymer.
Another object of the present invention is to provide a thin, flexible anode strip for use in electrochemical cells comprising an active material and a minor amount of an ethylene acrylic acid polymer.
The foregoing and additional objects will become more fully apparent from the following description.